BACKGROUND AND
OBJECTIVES: There are controversies regarding whether labor analgesia can
interfere with labor and the vitality of the newborn. The objective of this
study was the interaction between labor analgesia, using the continuous epidural
and combined spinal-epidural techniques with a small dose of local anesthetic,
and the type of delivery analyzing the newborn's weight and Apgar score.METHODS: The results of 168 labor analgesias (from January 2002 to January
2003) were analyzed. They were divided in 4 groups: G1 (n = 58), continuous
epidural and evolution to vaginal delivery; G2 (n = 69), combined spinal-epidural
and evolution to vaginal delivery; G3 (n = 25), continuous epidural and evolution
to cesarean; G4 (n = 16), combined spinal-epidural and evolution to cesarean.
G1 received 0.125% ropivacaine (12 to 15 mL), G2 received subarachnoid 0.5%
bupivacaine (0.5 to 1 mL) and sufentanil (10 mg). Epidural ropivacaine
0.5% for the vaginal delivery (8 mL) and for cesarean (20 mL). The patient's
age, weight, height, body mass index (BMI), gestational age, number of prior
pregnancies, and complications (arterial hypotension, bradycardia, and hypoxia)
and the newborn's weight and Apgar score (at 1, 5, and 10 minutes) were evaluated.RESULTS: The majority of pregnant women were primiparous and presented
with a term pregnancy (one with gestational age of 28 weeks and none post-term
pregnancy); weight, G2 < G4; and MBI, G2 £ G4. For the weight
of the newborn, G1 < G3 and G2 < G4, and for the Apgar score at 1st
minute, G1 > G3.CONCLUSIONS: If the analysis focuses the newborn's weight and Apgar score,
the techniques of analgesia, continuous epidural and combined spinal-epidural
with small doses of local anesthetic, do not interfere with the result of the
delivery.

Epidural analgesia
for labor is safe, effective, and has gained much popularity in the last decades,
replacing other methods, such as analgesia with inalational/anesthetics agents,
general anesthesia, and paracervical blockade1. There are controversies
as to whether this technique can interfere in the course of labor and in the
vitality of the newborn. Several studies have demonstrated elevated rates of
cesarean sections among patients who have received epidural analgesia2-4
while others were not able to prove it5-7.

A prospective study8
compared a group of pregnant women who received epidural analgesia with another
group who received intravenous opioids in which the dose was controlled by the
patients. It showed no difference in the rate of cesareans in both groups. A
bias in the selection of the sample could be one of the explanations for that
result  pregnant women who present severe pain early in labor were more
likely to receive epidural analgesia9,10.

Epidural analgesia
with small doses of local anesthetics (0.125% ropivacaine or with a smaller
concentration) is used to preserve muscular strength during the expulsive period,
while reducing pain, promoting maternal satisfaction, and has little interference
with the adaptive and neurological capabilities of the newborn11.
However, except for the patient's own satisfaction, the clinical benefits of
ambulation (due to a smaller motor blockade) in the progression and result of
labor are debatable, and need to be further investigated. But there are no doubts
that high concentrations (greater than 0.15%) of local anesthetics are undesirable
due to the resulting motor blockade that interferes with the maternal efforts
in expulsive phase12.

The combined spinal-epidural
technique of labor analgesia, with subarachnoid local anesthetic and opioids
after establishing the epidural access through the introduction of a catheter
to be used during the expulsive phase, promoting deep analgesia is effective
both in the first and in the second stages of labor12, is widely
used nowadays. The motor blockade is also less intense, favoring maternal ambulation
and the good development of labor.

The objective of
this study was to investigate the relationship between analgesia for labor using
the continuous epidural and combined spinal-epidural techniques, using small
doses of local anesthetics, and the type of delivery. The study of this relationship
was done analyzing the newborn's weight and Apgar score.

METHODS

This prospective
study was submitted to analysis, having being approved by the Ethics Committee
on Clinical Research of the Faculdade de Medicina de Botucatu to be carried
out by the Obstetrics Anesthesiology Service at University Hospital. Labor analgesia
was done by the epidural technique with small doses of local anesthetic (10
to 15 mL of ropivacaine at a maximum concentration of 0.125%) or combined spinal-epidural
administration of 0.5 hyperbaric bupivacaine (0.5 to 1 mL) and sufentanil (10
µg) during labor and the epidural administration of ropivacaine (maximum
concentration of 0.125%) when the patient demanded due to recurring pain. 0.5%
ropivacaine (8 and 20 mL, respectively) was used for the expulsive phase or
the cesarean section. All pregnant women received intravenous hydration with
Ringer's lactate before the blockade, being monitored with a sphygmomanometer,
a cardioscope using the DII lead derivation, and pulse oxymeter.

The choice of technique
was done at random and depended on the indication, for each case, of the team
on call each 24-hour period. The entire anesthetic procedure was recorded in
a database.

The results of
168 labors analgesia indicated by the University Obstetric team between January
2002 and January 2003 treated with the techniques described and performed by
Anesthesiology Service were analyzed.

The following parameters
related to the patient  age, weight, height, body mass index (BMI), gestational
age, and number of pregnancies  and related to the newborn  weight
and Apgar score at 1, 5, and 10 minutes were analyzed.

The development
of maternal bradycardia (cardiac frequency less than 50 bpm), hypotension (systolic
blood pressure 30% smaller than the normal for the patient), and hypoxia (hemoglobin
saturation below 90%) during labor analgesia were evaluated. The treatment of
these occurrences was also assessed (displacement of the uterus to the left,
increased infusion of Ringer's lactate, intravenous administration of fractioned
doses of ephedrine and oxygen).

Variance Analysis
with determination of F and p were used for the maternal variables (age, weight,
height, BMI, and number of pregnancies) and the newborn's weight. The mean and
standard deviation were studied to indicate a central tendency and variability,
respectively, in each group. The mean and percentiles P25 and P75
were used for the Apgar score (at 1, 5, and 10 minutes) of each group. Comparisons
among the groups were done by the Kruskal-Wallis non-parametric test to determine
p. Values of p < 0.05 were considered significant. Values of 0.5 < p <
0.10 were considered a significant tendency13.

The newborns' weight
and Apgar scores were also analyzed to determine the effects of each type of
delivery in each analgesia, i. e., for vaginal delivery or cesarean the mean
weights and Apgar scores after epidural combined spinal-epidural analgesia.
The same was done to determine the effects of analgesia in each type of delivery,
that is, for each technique, epidural or combined spinal-epidural, the mean
weight and the mean Apgar scores obtained in each type of delivery, vaginal
delivery or cesarean, were evaluated13.

RESULTS

The labors studied
did not present fetal malformations. Six patients in the G1 group were in their
second pregnancy; four of those had vaginal deliveries in the first pregnancy
and two had cesareans. The other women were primiparous (90%). All patients
in the G2 group were primiparous (100%). In G3, five patients were in their
second pregnancy and just one had had a cesarean in the first pregnancy. Hence,
80% were primiparous. In G4, just one patient had had a cesarean in the first
pregnancy and 94% were primiparous.

Statistical analysis
showed that there were no differences in the groups regarding maternal age and
height, and gestational age. In G1, one patient was in the 28th week
and one in the 35th week. In G2 six patients were in the 35th
week. In G3 one patient was in the 34th week. The other patients
were at term and no patient was post-term. Regarding maternal weight, there
was a tendency for G2 < G4 while G1 = G3 and intermediate between
the other two groups. The BMI of the patients in G2 < G4, which presented
a significant difference, and G1 = G3 were intermediates between the other two
groups (Table I).

Bradycardia and
hypoxia were not observed in any patient in the four groups. One patient in
G1, four in G3, and three in G4 presented hypotension, which was successfully
treated displacing the uterus to the left, increasing the rate of infusion of
Ringer's lactate, and with small doses of ephedrine (10 mg).

Table
II shows the mean and the standard deviation of the newborns' weights in
the four groups. There was no interaction between the two techniques of analgesia
for labor and both types of delivery. Statistical analysis demonstrated that
with both epidural and combined spinal-epidural the weights were G1 < G3
and G2 < G4, showing that the weights of the newborns delivered through the
vagina were smaller than those born through cesarean section.

To determine the
effects of the type of analgesia on each type of delivery, statistical analysis
showed that, on both vaginal delivery and cesarean section, the newborns' weights
were G1 = G2 and G3 = G4, i.e., the weight of the newborns whose mothers received
epidural analgesia were equal to those whose mothers received combined spinal-epidural
.

The statistical
analysis of the Apgar score (Table III) showed that it was
the same at 1, 5, and 10 minutes for both vaginal delivery and cesarean section
regardless of the type of analgesia (G1 = G2 and G = G4). However, the Apgar
score at 1 minute was significantly higher in newborns delivered by the vagina
and whose mothers received epidural analgesia (G1 > G3). The Apgar scores
at 5 and 10 minutes were equal for G1 and G3.

DISCUSSION

Table
I shows that the only statistically significant difference in the population
studied was in the BMI the pregnant who were treated with combined spinal-epidural,
G2 and G4, had a BMI significantly higher, but those who evolved for vaginal
delivery (G2) had a smaller BMI. However, the mean of the sample was overweight.
Hess et al.9 observed that women with higher BMI were more likely
to undergo cesarean section when they studied the relationship between labor
result and severe pain.

On the other hand,
if only the BMI of the pregnant women in this study is analyzed, the fetus may
be the one variable to influence the type of delivery. Thus, the BMI of the
mothers in G1 was equal to that of the mothers in G3, but the Apgar score of
the newborns in G1 (mothers who evolved to vaginal delivery) at 1 minute was
better than that of the ones in G3 (mothers who had cesareans sections) (Table
II).

The results on
table II demonstrate that
the babies delivered by the vaginal route were smaller than those born by cesarean
section, regardless of the type of analgesia administered (epidural or combined
spinal-epidural). The mean weight of the newborns in the vaginal delivery group
was 300 g smaller than those delivered by cesarean section. Based on these results,
one can assume that the weight, but not the type of analgesia administered,
would have influenced the type of delivery.

A study involving
112 women whose labor was induced evaluated the effects of epidural analgesia
on the duration of labor and on the maternal-fetal outcome14. There
was a marked reduction of complications during the intralabor period, but there
was no influence on the number of cesareans sections performed and in the Apgar
score of the newborns, despite de fact that the duration of labor was increased.
However, another local anesthetic, bupivacaine, was used, which provided for
greater motor blockade than ropivacaine, and higher doses and concentrations
than those recommended in our study were administered, which could explain those
results.

Kampe et al.15
established the cardiovascular effects on the mother and on the fetus of pregnant
women who received epidural analgesia with 0.75% ropivacaine and 0.5% bupivacaine
for elective cesarean section. Maternal BMI was the parameter that had greater
influence on the umbilical arterial pH. The authors believed that mothers with
elevated BMI were more likely to give birth to babies with lower pH because
the aortal-cava compression by the uterus should be greater due to the amount
of fatty tissue present or because the uterine incision could be made in a more
advanced stage for technical reasons.

There are several
causes of depression at birth. Biochemical indicators, which demonstrate the
presence of fetal acidosis, measure the most specific evidences of intra-uterus
hypoxia. On the other hand, the Apgar score, even though it is not a specific
indicator, evaluates the effects on the newborn16 that cannot be
obtained with biochemical measurements. In our study there were no cases of
fetal malformation and just one case of delivery in the 28th week
in G1, the most apparent causes of depression at birth.

An analysis of
1,000,000 births at term in Sweden16 indicated a strong influence
of the newborns' weight and gestational age on the resulting low Apgar score.
Low birth weight is a known risk factor for fetal compromise and a typical result
of chronic placental insufficiency17; meanwhile, macrosomia did not
stir the same interest. However, the authors discovered that weight deviation,
in either direction, at birth presented a similar risk for a low Apgar score
at 5 minutes. On the other hand, they indicated that fetal compromise on post-term
pregnancies had already been reported18 and their results are in
accordance with those previous reports the risk was obvious in 41-week pregnancies
and markedly increased in 43-week pregnancies. Newborns were not always exposed
to epidural analgesia, but the authors believed that this factor predisposes
to an increased risk of low Apgar scores at birth. But they did not report which
drugs were used for analgesia.

The low Apgar score
is frequently used as a synonym of neonatal asphyxia. Low scores at 1st
minute are often caused by temporary depression, while low scores at 5 and 10
minutes indicate the presence of clinically important complications, indicating
that the newborn did not respond well to the resuscitation maneuvers. The newborns
studied presented good Apgar scores at 1st minute. Those born under
the effects of epidural analgesia presented higher scores with vaginal deliveries
leading to the assumption that other problems unrelated to the technique of
analgesia probably influenced the type of delivery.

A study12
compared epidural bupivacaine and ropivacaine, both at 0.08% and associated
with fentanil 2 mg.mL-1, for labor analgesia and observed that the
evolution of the cervical dilation in pregnant women was 1.12 cm.h-1
and 1.18 cm.h-1, respectively. The capacity to ambulate was preserved
in all pregnant women in the ropivacaine group versus 75% in the bupivacaine
group. Neither group had Apgar scores at 5 minutes smaller than 7. The authors
also did not observe changes in maternal hemodynamics and concluded that labor
analgesia, used in the way they designed, did not affect the development of
the study. They believed, however, that the impact in ambulation and the method
of analgesia used (low concentration of local anesthetic and association to
fentanil) needed to be further investigated.

Regarding higher
concentrations of local anesthetics, which cause hemodynamic changes, Kampe
et al.15 considered that, if maternal arterial blood pressure and
cardiac frequency are clinically acceptable, i.e., within normal limits, they
do not influence birth. Therefore, by anesthetizing pregnant women undergoing
elective cesarean sections with epidural 0.5% bupivacaine or 0.75% ropivacaine,
they observed greater reduction in cardiac frequency in those women who received
ropivacaine but there were no differences between both groups regarding motor
blockade, level of sensitive blockade, umbilical cord blood pH, and Apgar score.

It is important
to remember that uterine activity decreases, especially the intensity of its
contractions, and labor is prolonged when analgesia is complicated by maternal
arterial hypotension (due to aortal-cava compression). Most pregnant women in
this study did not present hypotension, and when it occurred it was corrected
promptly14.

To finish, it can
be said that both techniques of analgesia studied, continuous epidural and combined
spinal-epidural with small doses of local anesthetics, did not influence the
type of delivery, if the analysis of that interaction focuses on newborn weight
and Apgar score. However, other studies are necessary in order to reach a consensus
on this matter.